/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineExternalUIInterface.h
Displays the UI that prompts the user to create an account
true if it was able to show the UI, false if it failed
bool ShowAccountCreationUI ( const int ControllerIndex, const [FOnAccountCreationUIClosedDelegate](API\Plugins\OnlineSubsystem\Interfaces\FOnAccountCreationUIClosedDelega-) & Delegate )